DISSOLUTION OF THORIUM IN MIXTURES OF HNO$sub 3$ AND HF

Laboratory measurements of dissolution rates of thorium in mixtures of nitric and hydrofluoric acids show that thorium can be dissolved with practicable time cycles in large-scale processing. The corrosion of stainless steel during the dissolution of thorium is acceptable, except that when the thorium is coated with Al-Si alloy, frequently used as a bonding material for aluminum cans, severe local corrosion of the stainless steel occurs at areas of contact with residual Al-Si. This contact corrosion does not occur when the cans are hot-press-bonded to the thorium without Al - Si. (auth)